The present invention relates to a pressurizer apparatus. More particularly, the present invention relates to a pressurizer apparatus for use in hip replacement surgery on a prepared medullary canal of a patient's femur during pressurization of bone cement injected into the prepared medullary canal.
Surgeons often pressurize bone cement during a prosthetic implant surgery to provide a cement mantle. See, for example, U.S. Pat. No. 4,488,549 entitled "Pressurization of Cement in Bones", to Lee et al. Such pressurization interdigitates the bone cement into the cancellous bone structure to increase the effectiveness of the cement mantle in which the prosthetic implant is placed. Surgeons also often prepare a bone, such as a femur during hip replacement surgery, for receiving the pressurized cement by first removing a head of the femur leaving an opening at a proximal end and then reaming the medullary canal. Surgeons have also used conventional sealing members to occlude the proximal end of the femur to obtain pressurization of the cement and the femur. See for example U.S. Pat. No. 4,815,454 entitled "Apparatus and Method for Injecting Bone Cement" to Dozier, Jr. Pressurization of the bone cement increases penetration of cement into the bone and creates a bone/cement interface to securely hold the prosthetic device in place.
Because patients' femurs are of various sizes, the proximal ends of prepared medullary canals also vary in size. It can be difficult for a surgeon to manipulate a single conventional sealing member to achieve a suitable seal with a variety of prepared medullary canals. Therefore, it can be necessary to have multiple conventional sealing members of various shapes and sizes present in the operating room to permit a surgeon or other medical personnel to select the appropriately sized conventional sealing member for a particular medullary canal. The presence of multiple differently sized conventional sealing member in the surgery room during hip replacement surgery can clutter the operating area. Handling multiple conventional sealing members can also be cumbersome to the surgeon. Furthermore, manufacturing multiple conventional sealing members and shipping the same to a location of the surgery can produce additional production and shipping costs.
What is needed is a pressurizer apparatus that is suitable for use on a number of shapes and size ranges of prepared medullary canals to seal the prepared canal during pressurization with a cement injection device.
According to the present invention, a pressurizer apparatus that is suitable for substantially sealing a prepared medullary canal having a proximal end during pressurization with a cement injection device is provided. The pressurizer apparatus comprises a body portion that includes dissimilar surfaces formed to engage the proximal end of the prepared medullary canal and to cover the medullary canal and a dissimilarsurface channel extending between the dissimilar surfaces. The dissimilar-surface channel is sized to receive at least a portion of the cement injection device therein to form a substantial seal between the medullary canal and the body portion.
According to another embodiment of the present invention, a pressurizer apparatus that is suitable for substantially sealing a prepared medullary canal having a proximal end and an outer lip extending about the medullary canal adjacent the proximal end during pressurization of the prepared medullary canal with a cement injection device having a guide portion is provided. The pressurizer apparatus comprises a one-piece body portion that includes a generally convex-shaped first surface formed to engage the lip, a second surface spaced apart from the first surface, and a channel extending between the first surface and the second surface. The channel is sized to receive the guide portion of the cement injection device therethrough.
According to yet another embodiment of the present invention, a pressurizer apparatus that is suitable for use with a cement injection device having a guide portion to substantially seal proximal ends of prepared medullary canals during pressurization of the prepared medullary canals is provided. The pressurizer apparatus comprises a body portion that includes an exterior surface formed to engage the proximal end and an inner surface that defines a first wall having a first diameter, a second wall having a second diameter that is greater than the first diameter, and at least one channel that extends through the exterior surface and incorporates the first and second walls. The second wall has a first end, a second end spaced apart from the first end, and a tab formed for engagement with the guide portion and that extends into the channel and is positioned to lie between the first and second ends of the second wall.
According to still another embodiment of the present invention, a method of sealing a prepared medullary canal for pressurization of bone cement is provided. The method includes the step of providing the prepared medullary canal, a cement injection device having a guide portion, and a pressurizer apparatus. The prepared medullary canal is defined by an end having a lip that defines an opening to the prepared medullary canal. The pressurizer apparatus has a first surface, a second surface spaced apart from the first surface, and an inner surface defining a channel extending between the first and second surfaces. The method further includes the steps of positioning one of the surfaces of the pressurizer apparatus on the lip of the prepared medullary canal, and inserting the guide portion of the cement injection device into the channel to create a substantial seal between the inner surface of the pressurizer apparatus and the guide portion and to permit the flow of bone cement from the guide portion into the medullary canal.
According to yet another embodiment of the present invention, a method is provided for substantially sealing prepared medullary canal for pressurization of bone cement. The method includes the step of providing a prepared medullary canal, a cement injection device having a guide portion, and a pressurizer apparatus. The prepared medullary canal includes a proximal end, an inner surface, and a lip adjacent the proximal end. The pressurizer apparatus has dissimilar exterior surfaces and an inner surface defining a channel between the dissimilar exterior surfaces. The method further includes the steps of selecting a dissimilar exterior surface of the pressurizer apparatus that is generally sized to form a substantial seal between the selected dissimilar exterior surface and the lip of the prepared medullary canal, positioning the selected dissimilar exterior surface on the lip of the prepared medullary canal, and inserting the guide portion of the cement injection device into the channel to create a substantial seal between the inner surface of the pressurizer apparatus and the guide portion and to permit the flow of bone cement from the guide portion into the medullary canal.
Additional features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.